As a general rule fasting and praying awaken in a person the desire for a more spiritual way of life. When the passions of the body become pacified, a person's mind is enlightened, and he begins to see his own shortcomings better. He becomes ashamed of his sinful deeds and bad habits, and he feels a strong desire to cleanse his soul through repentance before God.
We can appreciate better the importance of repentance when we remember that Christian teaching began precisely with the call to repent. The prophet John the Baptist preached: "Repent, for the kingdom of heaven is at hand" (Matthew 3:1-2). The Lord Jesus Christ began his preaching with the same words. "I indeed baptize you with water unto repentance," John the Baptist continues, "but He who is coming after me is mightier than I, whose sandals I am not worthy to carry. He will baptize you with the Holy Spirit and fire" (Matthew 3:11). That was a prophecy about the coming of the Holy Spirit on the day of Pentecost and the divine rebirth of Christians through their faith and repentance.
Indeed, after the descent of the Holy Spirit, the teaching of the Apostles was, first of all, the calling for repentance and the beginning of a new life in Jesus. The believers had to accept Jesus Christ as their Savior from the evil dominating the world. This is the very essence of Christianity. After the descent of the Holy Spirit on Pentecost, when the crowd asked, "What shall we do, brothers?" The Apostle Peter answered: "Repent, and each of you be baptized in the name of Jesus Christ, for the forgiveness of your sins, and you will receive the Gift of the Holy Spirit … Save yourselves from this corrupt generation!" (Acts 2:37-40). These words pointed out the deep, sinful sore in humanity, which can be healed only through repentance, rebirth in Christ, and unity with Him.
So, as we see, the Apostles called for profound changes in people's attitudes, a break with their past, and suppression of passions. The acceptance of Christ as our Savior requires a fundamental transfiguration of our thoughts and feelings: a sincere desire for a New Life in Christ. That is why the Church is so persistent in its calling to repentance during Lent. Repentance is the beginning of salvation. And fasting — being a restraint from gluttony, all kinds of excesses, and worldly concerns — contributes to true repentance! That is how the goal of our faith is reached, as Saint Paul teaches: "Therefore if anyone is in Christ, he is a new creature: former things have gone" (2 Corinthians 5:17).